I wasn't sure if there was a specific convention for it, but I chose to alias them when there is a commonly accepted romanization of their name (Kumuyu, for instance) and the English name was different (Camiuex for this example.)
Some of the updates (Xiao to Shao, for instance) are because the romanization strictly speaking is Shao (シャオ), and the official EN version name of that character is also Shao. I can only assume that Xiao was a name made up by someone random before the EN localization came out, however, since it neither matches the actual JP romanization, nor does it match the actual EN name, it seems like it would be prudent to abandon a name that's basically only used on Danbooru and not used anywhere in the game's actual community. This one's pretty understandable, though. However...
If I were to put it a bit more crudely, it seems like a few of the other names had some very unnecessary, and sometimes wrong, localization done on them pre-english release. Elegy (エジェリー = Ejeri, officially Ejaeli) and Betor (ヴェトル = Vetor/Vetol, officially Phoebe), for instance, are very unambiguously wrong.
Many of these forms of the names *only* exist on Danbooru, so it seems like it'd make a lot more sense just to correct them once now and have it match every other resource on the game.
With that said, it's probably not terrible if some of the older inaccurate names were preserved, as long as the tags on the actual pictures show either the proper JP or proper EN names (I'm not sure how the site software handles this).
I think there's a limited number (Sarasa == Thalatha) for instance that could be preserved as an alias... hrm. The JP romanization strictly is Saraasa, but as that set of characters are named after numbers, and Thalatha seems to be the acceptable romanization of the Arabic "three", it seems that they were going for the "th" sound rather than "s" in that case. I'll amend that one to be an alias.
This should be less of an issue moving forward, since new characters are released with their stuff already translated in the game nowadays, so it's mostly an issue for characters that existed prior to the official localization (which started partway through 2016).
If there are specific names in question, I would be happy to try to get ingame screenshots, or give direct links to the JP or EN wikis if you'd like to inspect the original names.